1. Field of the Invention
The present invention relates to an in-process diameter measuring apparatus for measuring the diameter of a to-be-processed surface of a work during the execution of a process of grinding an inner or outer peripheral surface of the work of a cylindrical shape or a shaft-like shape with the use of a grinding machine. The present invention specifically relates to an in-process diameter measuring apparatus having a measurement abnormality determining function for detecting the occurrence of an abnormality such as, for example, a bite of foreign matter in between a feeler of the sizing instrument and the work.
2. Description of Related Art
The grinding process with the use of a grinding machine is generally classified into three types; a rough grinding procedure for roughly grinding a workpiece to be processed, a fine grinding procedure for finely grinding a workpiece to be processed and a spark-out grinding procedure for finishing a deformed portion of, for example, a grindstone by the effect of a residual pressure. In addition the grinding process may include a dressing procedure for repairing the frictional wear of, for example, the grindstone. Such a grinding machine is generally equipped with a sizing device and has incorporated therein a scheme by which dimensional errors in the processed product are minimized to thereby increase the finished dimensional accuracy.
It has, however, been found that once a foreign matter such as, for example, grinding scrapes or ground particles is bitten in between a feeler of the sizing device and the workpiece during the processing, a dimensional error occurs in the finished dimensions and, if the dimensional error is large, the workpiece so processed with the dimensional error will become a defective product or require some adjustments. In order to avoid those inconveniences, the need is realized to detect a measurement abnormality and then to remove such measurement abnormality. The patent documents 1 and 2 listed below suggest such a method.
[Patent Document 1] JP Laid-open Patent Publication No. 2007-30103
[Patent Document 2] JP Laid-open Patent Publication No. 2002-239876